Modern electrochemical systems such as fuel cells, capacitors, sensors, and batteries can be constructed of electrochemical components that include a set of electrodes. In batteries, electrodes are typically made up of materials including an active material (i.e., an electrochemically-active material capable of undergoing reduction-oxidation), e.g., an oxide such as vanadium oxide, disposed in a polymeric matrix which may include an ionically-conductive polymer. The greater the amount of active material included in the electrode, the greater the capacity of the battery. Battery electrodes may further contain other useful materials including an electrically-conductive material (sometimes referred to as an “electrically-conductive diluent”) such as carbon, and an electrolyte salt such as lithium bis(trifluoromethanesulfonyl)imide, among various others.
Electrodes are often produced using standard coating techniques by dissolving or dispersing the active component, the electrically-conductive material, the electrolyte salt, and the polymer in a solvent and coating the solution onto a substrate. The materials are generally milled prior to being dispersed into the solvent and coated.
Some attempts have been made to prepare electrochemical components by extrusion methods. Such methods may include conditions of high shear and high temperature, making them prone to degrade materials of the electrochemical components, especially the polymer. See, e.g., U.S. Pat. Nos. 4,976,904, 5,804,116 and 5,749,927. Some of these have used solvents, plasticizers, liquids, or softening agents to avoid these conditions.
There is an ongoing need for new and improved methods of preparing electrochemical components such as electrodes, e.g., cathodes. Particularly desirable methods would allow the production of electrochemical components without degrading the components, most preferably could be accomplished with minimal or no use of solvents, and would produce an electrochemical component having useful properties, including, preferably, a high loading of active material.